Classic 50 - Acceleration

[Bryan0129]

1987+/- Mercury Classic 50<br />Can not read thje serial number. <br />4 Cyl. <br /><br />We had problems from the start when we got it. Motor would not exceed a certain rpm point, as if the variable timing was not shifting. Then all of a sudden, it ran great a few weeks later. Now it is way beyond problem bound than in the beginning.<br />Same problem just worse.<br /><br />Need to know what the correct compression psi is supposed to be... Having a lot of trouble with this motor and am trying to isolate the problem. <br />Compression readings:<br />#1 - 140psi<br />#2 - 142psi<br />#3 - 135psi<br />#4 - 133psi<br /><br />I can do/test just about anything with the motor so any suggestions would be great!

 

[AMD Rules]

Re: Classic 50 - Acceleration

Those compression readings look great. New from factory they are in the vicinity of 150 psig maximum, but anything over 110 shoudl run fine. They key is that they are all within 10% of each other.

 

[Bryan0129]

Re: Classic 50 - Acceleration

Thanks for the quick reply... Still not sure exactly what it could be. <br /><br />I went though and cleaned the carbs, and installed new jets. Carbs seem to be in good working order, in sequence. New plugs.. Coils tested good. New fuel lines and pump is working. I am curious about the hi/low spark adjuster because of the revving until a certain point and not exceeding that(tell me if that may be incorrect assumption). <br /><br />Thanks for any more help...

 

[Laddies]

Re: Classic 50 - Acceleration

The high speed winding in the stator could be bad or the switch box could be failing first you need to find out if you have spark on all cyl. if you do you could have a high speed jet plugged in one carb. ck for spark first and ohm test the system if you have a ohm meter we can give you the specs.

 

[Bryan0129]

Re: Classic 50 - Acceleration

We've got spark on all cylinders, and like i said prior. I cleaned the carbs thoroughly and checked to make sure all the passages were breathing. Had a buddy check the carbs as well at a local boat shop, so i think the carbs are good. It sounds like it runs like a champ, but it is like a electrical component is holding it back from achieving a higher rpm (I am not a outboard mastermind so i hope this doesn't sound far fetched), so let me go ahead and check out those specs so i can ohm out the components(will let you know what happens). Anything else I can try out, I am open to suggestions. Thanks...